Multi-functional flexible carbon fiber composites with controlled fiber alignment using additive manufacturing

This paper details a novel study and manufacturing approach of fiber alignment in flexible hybrid carbon fiber composites using Material extrusion. Varying carbon fiber volume fractions from 0 to 4 vol % was melt blended with a masterbatch of TPU + 10 wt% MWCNT followed by extrusion. The final extrudate was then filament wound onto a spool and two different filament layout orientations, 0° and 45°, were printed to compare their mechanical properties to validate the effect of fiber alignment during the printing process for these flexible fiber composites. The 0° printed composites exhibited up to 34% improvement in stiffness as compared to the 45° composite. To validate this fiber orientation, the flexible composite was textured using fiber-debonding and pullout phenomenon and the surfaces were visually and quantifiably characterized using SEM images and surface roughness respectively. To further elucidate the fiber alignment as indicated by the surface roughness, a water contact angle hydrophobicity test was conducted to prove that the 0° printed composite showed higher contact angle as compared with the 45° orientation, confirming greater entrapment due to fiber alignment at the surface. These composites are expected to find future potential in high strength and surface texturing applications.